Distyrenated alkyl aromatic hydrocarbon as lubricant



United States Patent 3,183,190 DISTYRENATED ALKYL AROMATIC HYDROCARBON AS LUBRICANT John W. Schick, Merchantville, and Edward A. Obcrright,

Woodbury, N.J., assignors to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. FiledNov. 2,1961, Ser. No. 149,532

4 Claims. (Cl. 252-59) at Mach 3 speeds (MIL-'lr-9236B) call for a lubricant that Will withstand temperatures up to about 400 F. It has been indicated that, in the Mach 3.5 to 4 speed range, oils will be required to withstand temperatures up to about 700 F.

Rockets, used in missiles and in space vehicles, require good lubrication. In these cases, the duration of high temperature performance is short. However, storage stability is necessary, because somerockets may remain on stand-by for several years.

It is the discovery of this invention that certain reaction products of styrenes and alkyl aromatic hydrocarbons are synthetic lubricants that are stable, even at elevated temperatures.

Accordingly, it is an object of this invention to provide a novel lubricant for jet engines and rockets. Another object is to provide a lubricant that is stable at elevated temperatures. A specific object is to provide a synthetic hydrocarbon lubricant for jet engines and rockets that is heat stable. A more specific object is to provide a stable lubricant obtained by reacting styrenes and alkylaromatic hydrocarbons. Other objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description.

In general, this invention provides, in the lubrication of jet engines and rockets, the improvement that comprises lubricating relatively moving parts of said jet engines and rockets with the distyrenated reaction product obtained from reacting a styrene reactant with a loweralkyl benzene.

In copending application, Serial No. 11,960, filed March 1, 1960, now United States Letters Patent No. 3,069,478, there was disclosed a process for reacting a styrene reactant and a lower-alkyl benzene in the presence of acidtreated montmorillonite clay or synthetic silica-alumina catalyst. The reaction is controlled to give a major yield of the adduct of one mole of a styrene with one mole of a lower-alkyl benzene (the monostyrenated product) and of the adduct of 2 moles of a styrene with one mole of a lower-alkyl benzene (the distyrenated product), with little production of higher polymer. It is the distyrea nated product, i.e., the 2:1 adduct of a styrene reactant and a lower-alkyl benzene that has been found to be a heat-stable lubricant for jet engines and rockets.

The styrene reactants contemplated herein are styrene and its ring-substituted derivatives. The ring substituents can be lower alkyl, halogen, i.e., substituents other than those which normally hinder alkylation reactions, such as amino groups which poison or react'with the catalyst. Non-limiting examples of the styrene reactant are styrene, vinyltoluene (p-methylstyrene), and dichlorostyrene.

3,l%3,l Patented May 11, 1965 The alkyl aromatic hydrocarbons utilizable herein are generally the alkylbenzenes, although alkyl naphthalenes can be used. The alkyl aromatic hydrocarbons can have up to three alkyl groups. The substituent alkyl groups can be straight chain or branched chain and can have up to 18 carbon atoms per alkyl group. However, the lower alkyl groups, i.e., butyl and lower are preferred. Nonlimiting examples of the aromatic hydrocarbon reactant are toluene, cumene, cymene, xylene, trimethylnaphthalene, ethylbenzene, methylnaphthalene, diethylbenzene, and butylbenzene.

The catalysts utilizable herein. are acid activated montmorillonite type clay and synthetic composites of silica and alumina. In the runs described hereinafter a nonswelling bentonite clay of the montmorillonite type, which has been activated by acid treatment to give a composition:

was used. This product is available in the activated state under the trade name Super Filtrol. The acid activation treatment is well known to those skilled in the art and is described more or less in detail by B. A. Stagner in The Science of Petroleum, volume III, page 1699 (Oxford Press) (1938). For the activation of small quantities of clay a similar treatment may be used. Thus, one kilogram of bentonite is boiled with 2,000 cubic centimeters of 17 percent sulfuric acid for three hours. The mixture is filtered and the clay washed with distilled water until the filtrate is substantially free from acid (0.2 to 0.5 percent acid). The clay is then dried to a moisture content of about 15 percent and ground to pass a 200 mesh screen. When the acid treated clay is washed with hard water after the acid is neutralized, the clay is injured by absorbing basic ions from the Water.

When only. a portion of the total extractable material is leached from the clay by the acid, the maximum'activity is developed. The optimum concentration of the acid is about 15 percent to about 20 percent. Sulfuric acid and hydrochloric acid are the most economical to use although sulfuric acid is somewhat slower than hydrochloric. a

The other type of material found effective as a catalyst herein are synthetic composites of silica and alumina which are acidic in nature. Such composites will contain about 7 percent and about 15 percent, by weight, of alumina, the balance being substantially silica. There appears to be nothing critical about the manner in which these composites are prepared. They may be made by any of the usual methods well known to those skilled in the manufacture of catalysts. A feasible method for preparing the catalyst involves adding an aqueous acidic solution, containing the required amount of aluminum salt, to an aqueous solution of sodium silicate, thus precipitating the silica and alumina simultaneously. This type of operation can be carried out in accordance with the method known in United States Patent No. 2,3 84,946 to produce the catalyst in a hydrogel bead form.

Another modified form of the synthetic silica-alumina composite is one having incorporated into the silicaalumina sol a small amount of powdered material insoluble in the sol. Such catalysts are described in United States Letters Patent No. 2,900,349.

Concentrations of catalyst, based upon total charge, as low as 0.7 weight percent are effective. Higher catalyst concentrations are, however, more effective. Generally,

the reaction can be carried out using catalyst weight con centrations varying between about 0.7 percent and about 5 percent, and preferably between about 2 percent and about 3 percent for maximum yields.

The reaction between the styrene reactant and the loweralkyl benzene is carried out at temperatures between about 80 C. and about 150 C., although the preferred reaction occurs between about 135 C. and about 150 C. The molar ratio of lower-alkyl benzene to styrene reactant is between 1:1 and 1.521. The lower ratio favors distyrenated product. a

After separation of liquid product from catalyst, as by filtration, the liquid product is distilled. The unreacted starting materials are first removed. Then, the residual liquid product is subjected to distillation under reduced pressure. The first distillation plateau yields the monostyrenated product (1:1 adduct). At the second distillation plateau, the desired distyrenated product (2:1 adduct) is distilled over. In the case of a preferred product from styrene and xylene, the desired 2:1 adduct distilled at 450 C. (842 F.) at atmospheric pressure.

EXAMPLE 1 A mixture of 300 g. (2.93 moles) xylene and 10 g. (5 weight percent) acid-treated clay of the montmorillonite type (Super Filtrol) was placed in a reaction vessel and agitated. The mixture was heated to about 135 C. and 208 g. (2.0 moles) styrene was added portionwise over a period of about 2 hours. As the reaction was exothermic, the rate of addition was adjusted so that little or no external heating or cooling was needed. After the styrene was all added, the reaction mixture was maintained at about 150 C. for an additional 1 hour. The mixture was cooled and filtered to remove the catalyst. The filtrate was topped to remove unreacted xylene and vacuum distilled. After removing the monostyrenated product (1:1 adduct), boiling at 380 C. at 760 mm. mercury pressure, the desired distyrenated product (2:1 adduct) boiling at 450 C. at 760 mm. mercury pressure was obtained. The distyrenated product was subjected to gas chromatography and was found to be a mixture of isomers (about 24 isomers possible). This synthetic lubricant producthad a specific gravity of 1.0298, a pour point (ASTM D97-57) of F., a flash point (ASTM D9257) of 415 F., a fire point (ASTM D9257) of- 460 F., kinematic viscosity (ASTM D445-60) of 192.5 cs. 100 F. and of 7.13 cs. 210 F., and a refractive index, n of 1.5894. 5

EXAMPLE 2 A portion of the distyrenated product of Example 1 was subjected to radiation from a G. E. Resonant Transformer. After being subjected to a total radiation dosage of 1 10 rads, the oil showed a viscosity increase of 42.3%. A commercial hydraulic (petroleum) oil, under 4 Military Specification MIL-G-25760A (September 14, 1960), except the test was run at 600 r.p.m. for 30 minutes. Pertinent results are set forth in Table I.

For comparison, a solvent, refined mineral lubricating oil (Mid-Continent base) was also subjected to this test. Test results are set forth in Table I.

EXAMPLE 4 Portions tof the synthetic lubricant (distyrenated prod not) of Example 1 were subjected to a catalytic oxidation test. In this test, a 25 cc. sample of the test oil is placed in a 200 x 25 mm. test tube. Then there are immersed (a) 15.6 sq. in. of sandblasted iron wire, (b) 0.78 sq. in. of polished copper wire, (0) 0.87 sq. in. of polished aluminum wire, and (d) 0.16 sq. in. of polished lead surface. The lead is carefully weighed. The oil is heated to the prescribed temperature and maintained at that temperature, while dry air is being passed therethrough, at a rate of 10 liters per hour, for the prescribed period of time. Three conditions of temperature and time are used, namely, (1) 260 F. for 40 hours, (2) 325 F. for 24 hours, and (3) 375 F. for 16 hours.

In each test, there are noted the neutralization number (ASTM D974-58T), a'measure of the amount of corrosive acid formed, the loss in weight of the lead specimen, and changes in viscosity. Pertinent data for the synthetic lubricant of Example 1 are set forth in Table II.

For comparison, tests were also run on a mineral lubricating oil, an uninhibited, solvent refined Pennsylvania oil. Another series of tests were run on di(2-ethylhexyl) sebacate, a currently accepted jet engine lubricant. Test data are set forth in Table II.

Table II CATALYTIC OXIDATION TEST Neut. No. K.V. 210 F., cs.

Time, Temp.,

Hrs. I Percent Pb Initial Final Initial Final Vls. Loss,

Inc. mg.

40 260 0.05 4. 0 7. 69 20. 47 157 21. 4 011 of Ex. 1 24 325 0. 05 2. 1 7. 69 1s. 79 144 25. 2 16 375 0. 05 1.9 7. 69 23. 56 205 40 260 0. 05 12. s 8.36 17. 85 113 200 Mineral Oil 24 325 0. 05 9. 8 s. 36 17.70 111 132 16 375 0. 05 10. a s. 36 23. 40 180 D1(2-ethylhexy1) 40 260 0. 15 a2. 8 3. 35 5. a3 59 105 sebacate 24 325 0. 15 35. 4 3. 36 6. 27 87 16 375 0. 15 26. 0 3.36 11.17 232 47 the same dosage, showed 204% vlscosity increase. A pro- EXAMPLE 5 posed synthetic lubricant, bis(m-phenoxyphenyl) ether, showed 44% vlscosity increase under a milder dosage of 5.5 10 rads.

EXAMPLE 3 A portion of the synthetic lubricant (distyrenated product) of Example 1 was subjected to the Shell Four Ball Test. This test is carried out as described in US.

and then cooled, in a nitrogen atmosphere, in a desiccator.

The kinematic viscosity of the test oil is determined before and after heating. The percent loss in viscosity shows the stability of the oil. The test on the oil of Example 1 was carried out at 700 F. Pertinent data are set forth in Table III.

Table III THERMAL STABILITY TEST Original: Oil of EX. 1 K.V. 100 F., cs 192.5 K.V. 210 F., cs. 7.13

Held 700 F. for 90 minutes:

K.V. 100 F., cs 186.7

Percent decrease 3.0 K.V. 210 F., cs. 7.06 Per-cent decrease 1.0

From the foregoing data, it will be appreciated that distyrenated lower-alkyl benzenes are valuable lubricants for jet engines and rockets. They have a community of properties, including resistance to radiation, antiwear prop erties, oxidation stability, and thermal stability.

Although the present invention has been described with preferred embodiments, it will be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview and scope of the appended claims.

What is claimed is:

1. In the lubrication of jet engines and rockets, the improvement that comprises lubricating relatively moving parts of said jet engines and rockets with the distyrenated re action product obtained by reacting styrene reactant with an alkyl aromatic hydrocarbon selected from the group consisting of alkylbenzenes having between 1 and 18 carbon atoms per alkyl group and alkylnaphthalenes having between 1 and 18 carbon atoms per alkyl group, said alkyl aromatic hydrocarbon having 1-3 alkyl groups, in the presence of a catalyst selected from the group consisting of an acid-treated bentonite non-swelling montmorillonite clay and synthetic silca-alumina containing between about 7 percent and about 15 percent alumina by weight, at a temperature varying between about C. and about 150 C.; the molar ratio of said alkyl aromatic hydrocarbon to said styrene reactant being between about 1:1 and about 1.5: l and the amount of said catalyst being between about 0.7 percent and about 5 percent of the weight of the total reactants.

2. The improvement defined in claim 1 wherein said alkyl aromatic hydrocarbon reactant is a lower-alkyl benzene.

3. In the lubrication of jet engines and rockets, the improvement that comprises lubricating relatively moving parts of said jet engines and rockets with the distyrenated reaction product obtained by reacting styrene with a loweralkyl benzene having 13 alkyl groups in the presence of an acid-treated bentonite non-swelling montmorillonite clay, at a temperature varying between about C. and about 0.; the molar ratio of said lower-alkyl benzene to said styrene being between about 1:1 and about 1.5 :1 and the amount of said acid-treated clay being between about 0.7 percent and about 5 percent by Weight of the total reactants.

4. The improvement defined in claim 3 wherein said lower-alkyl benzene is xylene.

References Cited by the Examiner UNITED STATES PATENTS 2,564,488 8/51 Mahan 260671 2,742,516 4/56 Schneider 25259 X 2,767,230 10/56 Brown et al. 260-6l7 2,930,820 3/60 Aries 260617 FOREIGN PATENTS 585,073 l/47 Great Britain.

ALPHONSO D. SULLIVAN, Primary Examiner.

JETALD GREENWALD, DANIEL E. WYMAN,

Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 'Patent No. 3,183,190 May 11, 1965 John W. Schick et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, Table I, line 5 thereof, for "m.p.m,-600" read r.p.m.--600 same column 4, line 33, for "0.16" read Signed and sealed this 4th day of January 1966 (SEAL) Attest:

ERNEST W. SW'IDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN THE LUBRICATION OF JET ENGINES AND ROCKETS, THE IMPROVEMENT THAT COMPRISES LUBRICATING RELATIVELY MOVING PARTS OF SAID JET ENGINES AND ROCKETS WITH TEH DISTYRENATED REACTION PRODUCT OBTAINED BY REACTING STYRENE REACTANT WITH AN ALKYL AROMATIC HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF ALKYLBENZENES HAVING BETWEEN 1 AND 18 CARBON ATOMS PER ALKYL GROUP AND ALKYLNAPHTHALENES HAVING BETWEEN 1 AND 18 CARBON ATOMS PER ALKYL GROUP, SAID ALKYL AROMATIC HYDROCARBON HAVING 1-3 ALKYL GROUPS, IN THE PRESENCE OF A CATALYST SELECTED FROM THE GROUP CONSISTING OF AN ACID-TREATED BENTONITE NON-SWELLING MONTMORILLONITE CLAY AND SYNTHETIC SILCA-ALUMINA CONTAINING BETWEEN ABOUT 7 PERCENT AND ABOUT 15 PERCENT ALUMINA BY WEIGHT, AT A TEMPERATURE VARYING BETWEEN ABOUT 80*C. AND ABOUT 150*C.; THE MOLAR RATIO OF SAID ALKYL AROMATIC HYDROCARBON TO SAID STYRENE REACTANT BEING BETWEEN ABOUT 1:1 AND ABOUT 1.5:1 AND THE AMOUNT OF SAID CATALYST BEING BETWEEN ABOUT 0.7 PERCENT AND ABOUT 5 PERCENT OF THE WEIGHT OF THE TOTAL REACTANTS. 